JP7229723B2 - IMAGE PROCESSING DEVICE, CONTROL METHOD THEREOF, AND PROGRAM - Google Patents

Description

The present invention relates to an image processing apparatus , its control method, and a program.

2. Description of the Related Art An image forming apparatus that reads a document conveyed from an automatic document feeder is known. 2. Description of the Related Art In an image forming apparatus, when reading a document, various situations may easily occur depending on the thickness of the document. For example, when the document conveyed from the automatic document feeder is thick paper, the load on the conveying roller increases at the curved portion of the conveying path, causing jamming. In addition, when the documents fed from the automatic document feeder are thin paper, it takes time for the documents ejected to the paper ejecting section to drop completely due to the light weight of the documents themselves. Collision with the leading edge of the document causes a jam or stacking error. Conventionally, in order to prevent the occurrence of situations such as jams and stacking failures during transport of the documents, the transport speed of the documents is controlled according to the thickness of the placed documents (see Japanese Patent Laid-Open No. 2002-100001).

On the other hand, when the document to be read by the image forming apparatus is thin paper, the characters and images on the back side are read through, and the image data and printed matter in which the characters and images on the back side show through (hereinafter referred to as "show-through data"). is output. In response to such problems, an image forming apparatus having a show-through prevention function has been developed. This image forming apparatus performs image processing for removing the show-through on the image data obtained by reading when the show-through prevention function is enabled by the user's setting.

JP-A-6-24604

The show-through prevention function is set by the user, but the user does not notice the show-through of the characters or images on the back side until he or she checks the output image data or printed matter. For this reason, conventionally, when reading a thin document, the reading process is frequently started without the show-through prevention function being set to be effective. As a result, even if it is possible to prevent the occurrence of jams and stacking failures during document transport, it is not possible to reliably prevent the output of show-through data.

An object of the present invention is to set the document transport speed to a second transport speed that is lower than the first transport speed when the document placed on the document tray has a second thickness that is thicker than the first thickness . To provide a mechanism capable of preventing a user from forgetting to set the thickness of a document in an apparatus that requires a thickness of a document .

In order to achieve the above object, an image processing apparatus of the present invention is an image processing apparatus having transport means for transporting a document placed on a document tray and reading means for reading an image of the document transported by the transport means. and an object for accepting the thickness of the document from a user . display means for displaying at a predetermined timing on the condition that it is detected that the document has been received; and when the thickness of the document received by the object is a second thickness that is thicker than the first thickness, the transport means causes the document to be transported at a second transport speed slower than the first transport speed. and control means for conveying the document at a conveying speed .

According to the present invention, when the thickness of the document placed on the document tray is the second thickness that is thicker than the first thickness, the document is transported at a second transport speed that is lower than the first transport speed. It is possible to prevent the user from forgetting to set the thickness of the document in an apparatus that requires the thickness of the document to be set .

1 is an external view of an image forming apparatus according to an embodiment of the invention; FIG. 2 is a cross-sectional view schematically showing the configuration of an ADF and an image reading unit in FIG. 1; FIG. 2 is a block diagram schematically showing the configuration of the image forming apparatus of FIG. 1; FIG. FIG. 4 is a functional block diagram for realizing show-through removal in the image processing circuit of FIG. 3 ; FIG. 4 is an external view of an operation unit in FIG. 3; It is an example of the screen displayed on the LCD touch panel of FIG. FIG. 4 is a flow chart showing the procedure of scan control processing executed by the controller unit of FIG. 3; FIG. 6 is a diagram showing an example of a notification screen displayed on the LCD touch panel in FIG. 5; FIG. 4 is a flow chart showing a procedure of scanning processing executed by the image reading unit of FIG. 3; FIG. 4 is a flow chart showing a procedure of image processing for removing show-through performed by the controller unit shown in FIG. 3; FIG. FIG. 11 is a diagram for explaining determination of a background level in step S1004 of FIG. 10;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external view of an image forming apparatus 100 according to an embodiment of the invention. The image forming apparatus 100 includes an automatic document feeder 101 , an image reading section 103 and an image forming section 104 . In the following description, the auto document feeder will be referred to as ADF.

In the image forming apparatus 100, when the user sets a document on the document setting tray 102 of the ADF 101 and instructs the start of reading using the operation unit 326 shown in FIG. Send a document reading instruction. The image reading unit 103 feeds the document sheet by sheet from the document setting tray 102 of the ADF 101 based on the received document reading instruction, and performs the document reading operation. The image forming apparatus 100 can also read a document placed on a document platen glass 221 shown in FIG. 2, which will be described later.

The image reading unit 103 emits light from an illumination lamp (not shown), and inputs the reflected light obtained by exposing and scanning the image on the document to a linear image sensor (CCD sensor) (not shown) to read the image. Converts information into electrical signals. The image reading unit 103 also converts the converted electric signal into a luminance signal of each color of R, G, and B, and outputs the luminance signal as image data to the controller unit 321, which will be described later.

The image forming unit 104 is an image forming device that forms image data received from a controller unit 321 (to be described later) on paper. The image forming method in this embodiment is an electrophotographic method using a photosensitive drum (not shown) or a photosensitive belt (not shown). The image forming section 104 also includes a paper feed unit 105 , a paper discharge unit 106 , and a finisher unit 107 . The paper feed unit 105 includes a plurality of cassettes with different sizes and orientations of paper to be stored. Printed materials are discharged to the discharge unit 106 and the finisher unit 107 .

FIG. 2 is a cross-sectional view schematically showing the configuration of the ADF 101 and image reading unit 103 in FIG. In addition, in FIG. 2, the internal configuration is transparently shown for easy understanding.

2, the ADF 101 includes a document tray 201, a separation pad 202, a document detection sensor 203, a distance measurement sensor 204, a separation sensor 205, and a paper feed roller 206. FIG. A document bundle S composed of one or more document sheets is stacked on the document tray 201 . Separation pad 202 prevents document stack S from protruding from document tray 201 and advancing downstream before the start of transport of the document. A document detection sensor 203 detects that a document is placed on the document tray 201 . A distance measuring sensor 204 measures the distance to the uppermost surface of the stack of documents S. FIG. A separation sensor 205 detects that the document has passed the separation roller 207 .

The paper feed roller 206 drops onto the document surface of the document bundle S stacked on the document tray 201 and rotates. As a result, the uppermost document of the stack of documents S is fed. The document conveyed by the paper feed roller 206 is separated into one sheet by the action of the separation roller 207 and the separation pad 202 . This separation is achieved, for example, by a retard separation technique. Note that if the separation sensor 205 cannot detect the document even after a predetermined time (t1) has elapsed from the start of transportation, the ADF 101 stops driving the paper feed roller 206 and the like. The predetermined time (t1) is a time in consideration of the arrival time and delay from the start of transportation predicted according to the transportation speed to the separation sensor 205 .

The document separated by the action of the separation roller 207 and the separation pad 202 is conveyed to the registration roller 209 by the conveyance roller 208 and is abutted against the registration roller 209 . As a result, the document is formed in a loop shape, and the skew of the document is eliminated. On the downstream side of the registration rollers 209 , a paper feed path is arranged for conveying the document that has passed through the registration rollers 209 toward the reading glass 210 .

The document conveyed to the paper feed path is conveyed onto the platen by the large roller 211 and the conveying roller 212 . The large roller 211 contacts the scanning glass 210 . The document transported by the large roller 211 passes through the transport roller 213 , moves between the roller 214 and the moving glass, and is discharged to the document discharge tray 216 via the discharge flapper and the discharge roller 215 .

The ADF 101 according to the present embodiment reads the back side image of the document by reversing both sides. The ADF 101 moves the document to the reverse path 217 by rotating the discharge roller 215 in the reverse direction and switching the discharge flapper while the document is caught by the discharge roller 215 . The moved document is abutted against the registration rollers 209 from the reversing path 217, and the document is again formed into a loop shape, thereby eliminating the skew in the transport of the document. After that, the ADF 101 moves the document to the feeding glass 210 again using the conveying roller 212 and the large roller 211 , so that the rear surface of the document can be read by the feeding glass 210 .

The document tray 201 also has a guide regulation plate 218 that can slide in the sub-scanning direction of the stacked document bundle S, and a document width detection sensor (not shown) that detects the document width in conjunction with the guide regulation plate 218 . is provided. The document size of the document bundle S stacked on the document tray 201 is determined by the document width detection sensor and the pre-registration sensor 219 . Further, a document length detection sensor (not shown) provided on the transport path of the ADF 101 detects the document length based on the transport distance from the detection of the leading edge of the document being transported to the detection of the trailing edge of the document being transported. The document size is determined based on the detection result of the width detection sensor.

The image reading unit 103 optically reads image information recorded on the document on the platen glass 221 by scanning the optical scanner unit 220 in the sub-scanning direction (see arrow A in FIG. 2). Documents placed on the ADF 101 are conveyed one by one to the reading center position of the ADF 101 . At this time, the optical scanner unit 220 is moved to the reading center position, and the document is read at the reading center position. A document placed on the ADF 101 or a document placed on the platen glass 221 is read by an optical system provided in the optical scanner unit 220 . The optical system comprises a flow reading glass 210 , a platen glass 221 , an optical scanner unit 220 , mirrors 222 and 223 , a lens 224 and a CCD sensor unit 225 . Optical scanner unit 220 comprises lamp 226 and mirror 227 . Image information read by the optical system is photoelectrically converted and output as image data to the controller unit 321, which will be described later. A white board 228 provided in the image reading unit 103 creates white level reference data by shading. In this embodiment, the CCD sensor unit 225 is composed of a color CCD 229 and a monochrome CCD 230 .

FIG. 3 is a block diagram schematically showing the configuration of the image forming apparatus 100 of FIG. 1. As shown in FIG. In FIG. 3, the ADF 101 has a CPU 300, a ROM 301, a RAM 302, a motor 303, a sensor 304, a solenoid 306, and a clutch 307. CPU 300 , ROM 301 , RAM 302 , motor 303 , sensor 304 , solenoid 306 and clutch 307 are interconnected via bus 308 . The ADF 101 also has an input port (not shown) and an output port (not shown). A sensor 304 representing various sensors in FIG. 2 is connected to the input port. A motor 303, a solenoid 306, and a clutch 307 for driving various conveying rollers shown in FIG. 2 are connected to the output port.

The CPU 300 controls paper transport according to a control program stored in the ROM 301 . The CPU 300 performs serial communication with the CPU 310 of the image reading unit 103 via the control communication line 309 and transmits/receives control data to/from the image reading unit 103 . For example, the CPU 300 transmits to the image reading unit 103 an image leading edge signal that serves as a reference for the leading edge of the document image data. Further, the CPU 300 receives control data received from the CPU 310 of the image reading unit 103, and transmits detection results of the sensor 304 to the image reading unit 103 according to the received control data. The ROM 301 stores control programs and fixed parameters. A RAM 302 stores input data and work data.

The image reading unit 103 includes a CPU 310 , a ROM 311 , a RAM 312 , a paper gap correction unit 313 , an image processing unit 314 , an optical system motor drive unit 315 , a lamp 226 , a CCD sensor unit 225 and an image memory 316 . The CPU 310 , ROM 311 , RAM 312 , paper gap correction section 313 , image processing section 314 , optical system motor drive section 315 and lamp 226 are connected to each other via a bus 320 . The image processing section 314 is connected to the CCD sensor unit 225 and image memory 316 .

A CPU 310 performs all controls related to the image reading unit 103 . The ROM 311 stores programs. A RAM 312 is a non-volatile storage device, and is used as a work area for the CPU 310, for example. The paper gap correction unit 313 performs paper gap correction. The optical system motor drive section 315 is a driver circuit for driving the optical system drive motor. The CPU 310 controls the optical system motor drive section 315 and controls the CCD sensor unit 225 via the image processing section 314 to execute image reading processing.

In addition, the CPU 310 transmits a command regarding paper transport control to the CPU 300 of the ADF 101 via the control communication line 309 in order to realize paper transport. Upon receiving the command, the CPU 300 monitors the sensor 304 installed on the transport path, and drives the transport motor 303, solenoid 306, and clutch 307, thereby realizing paper transport. In this manner, the CPU 310 controls paper transport by the ADF 101 and image reading by the image reading unit 103 .

An image signal formed on the CCD sensor unit 225 through the lens 224 is converted into digital image data. The converted image data is subjected to various types of image processing, such as shading processing and processing for detecting and correcting streak images in the image data, by an image processing unit 314 , and written to an image memory 316 . The data written in the image memory 316 are sequentially transmitted to the controller section 321 via the image communication line 317 . In addition, the CPU 310 adjusts the notification timing of the image leading edge signal, which serves as the reference for the leading edge of the document image data, and transmits it to the controller section 321 via the control communication line 318 . The notification timing of the image destination signal received from the ADF 101 is similarly adjusted by the CPU 310 and transmitted to the controller unit 321 via the control communication line 318 .

CPU 310 controls image processing unit 314 . The CPU 310 also controls the CCD sensor unit 225 by transmitting control signals to the CCD sensor unit 225 via the image processing section 314 . In the process of scanning the document image with the CCD sensor unit 225, analog image signals are read by the CCD 229 for color and the CCD 230 for monochrome. The read analog image signal for each line is output to the CCD control section 319 . The CCD control unit 319 converts the received analog image signal into digital image data and outputs the digital image data to the image memory 316 . The image memory 316 transmits the received digital image data to the controller section 321 via the image communication line 317 .

The CPU 310 performs serial communication with the CPU 322 of the controller section 321 via the image communication line 317 and transmits and receives control data to and from the controller section 321 . The CPU 310 detects an abnormality in the shape of the document being conveyed according to the control data received from the CPU 322 . In the detection of the shape abnormality, the CPU 310 calculates the distance to the top surface of the document stack S measured for each document before the start of transport and the distance to the top surface of the document stack S measured after a certain time (t2) after the start of transport. Calculate the difference between If the difference (d1) is greater than or equal to a certain value, the CPU 310 determines that the document has an abnormal shape, and notifies the CPU 322 of the determination result.

A controller unit 321 controls the entire image forming apparatus 100 including the ADF 101 , the image reading unit 103 and the image forming unit 104 . The controller section 321 includes a CPU 322 , an image processing circuit 323 , a scanner IF 324 , an image memory 325 , an operation section 326 , a RAM 327 , a ROM 328 , a printer IF 329 and an HDD 330 . CPU 322 , image processing circuit 323 , scanner IF 324 , image memory 325 , operation unit 326 , RAM 327 , ROM 328 , printer IF 329 and HDD 330 are connected to each other via bus 331 . The CPU 322 loads the program stored in the HDD 330 onto the RAM 327 and executes the loaded program. A RAM 327 is a non-volatile storage device and used as a work area for the CPU 322, for example. The ROM 328 stores programs. The controller unit 321 stores the image data received from the image reading unit 103 via the image communication line 317 in the image memory 325 .

The image processing circuit 323 image-converts the image data stored in the image memory 325 . The image processing circuit 323 performs, for example, rotation processing, resolution conversion processing, scaling processing, and color space conversion processing on image data. Rotation processing is processing for rotating an image of 32×32 pixels by a specified angle. Resolution conversion processing is processing for converting the resolution of an image. The scaling process is a process of scaling an image in the image conversion process performed by the image processing circuit 323 . The color space conversion process is a process of performing a matrix operation on an image input with multiple values and converting a YUV image into a Lab image using an LUT. The color space conversion process has a 3×8 matrix operation and a one-dimensional LUT, and can implement background removal and show-through removal. The image processing circuit 323 returns the converted image data to the image memory 325 .

FIG. 4 is a functional block diagram for realizing show-through removal in the image processing circuit 323 of FIG. In this embodiment, the image processing circuit 323 discriminates the background level in the image data, executes an operation for removing the background corresponding to the background level, and converts the input luminance value to the output luminance value, thereby converting the background image into the output luminance value. Remove reflections. When the document is pulled into the feeder and read by the CCD sensor unit 225 , the image signal generator 401 converts the read image signal into a luminance signal and outputs the luminance signal to the histogram generator 402 . Histogram generation means 402 extracts pixels at an arbitrary sampling pitch based on the received luminance signal and counts the luminance levels to generate a histogram. Note that if the document size is not specified before scanning is started, the image signal generation unit 401 performs processing with the length of the image of the maximum size assumed.

In the image processing circuit 323, when the document size is determined during image signal generation, the document size detecting means 403 notifies the histogram generation area changing means 404 of the document size. Histogram generation area change means 404 changes the area of the image data sampled by histogram generation means 402 to the document size notified from document size detection means 403 . After the document is scanned, the background level determining means 405 determines the background level from the histogram sampled by the histogram generating means 402 . The background level determination means 405 sets the background removal processing means 406 with a coefficient for removing the background based on the determined background level. A background removal processing unit 406 removes the background of the image data based on the set coefficient.

Returning to FIG. 3 , the image forming unit 104 conveys the recording paper, prints the image data as a visible image on the recording paper, and discharges the printed material to the outside of the image forming apparatus 100 . The image forming section 104 includes a control section 332 and a marking unit 333 in addition to the discharge unit 106, the paper feeding unit 105, and the finisher unit 107 shown in FIG. The controller 332 , marking unit 333 , paper discharge unit 106 and paper feed unit 105 are connected to each other via a bus 334 . A control unit 332 controls the image forming unit 104 . The control section 332 transmits a destination signal to the controller section 321 via the control communication line 335 when the marking unit 333 is ready for image formation. The paper discharge unit 106 has a function of outputting printed matter to the outside of the image forming apparatus 100 . The marking unit 333 has a function of transferring and fixing image data onto paper. The marking unit 333 transfers and fixes the image data received via the image communication line 336 onto the paper. A finisher unit 107 performs punch processing and sort processing.

FIG. 5 is an external view of the operation unit 326 in FIG. 3. As shown in FIG. The operation unit 326 includes an LCD touch panel 500 , ten keys 501 , an ID key 502 , a reset key 503 , a guide key 504 , a user mode key 505 , an interrupt key 506 , a start key 507 , a stop key 508 and a power saving key 509 . The operation unit 326 also includes a counter confirmation key 510 , an LED 511 , an error LED 512 and a power LED 513 .

The LCD touch panel 500 is an input device having a touch panel attached on a liquid crystal display. The LCD touch panel 500 displays functions, image data, and the like in operating the image forming apparatus 100 . A numeric keypad 501 is a hard key for inputting numerical values from 0 to 9. FIG. The ID key 502 is used to input a department number and password mode when the image forming apparatus 100 is under department management. A reset key 503 is a hard key for resetting the set mode. A guide key 504 is a hardware key for displaying an explanation screen for each mode installed in the image forming apparatus 100 . A user mode key 505 is a hard key for displaying a user mode screen on the LCD touch panel 500 . On the user mode screen, it is possible to make user-specific settings regarding the image forming apparatus 100 .

An interrupt key 506 is a hard key for interrupt copying. A start key 507 is a hard key for starting a copy or scan operation. A stop key 508 is a hard key for stopping a job being executed. A power saving key 509 is a hardware key for switching the image forming apparatus 100 to a power saving state or recovering from the power saving state. Counter confirmation key 510 is a hard key for displaying a count screen on LCD touch panel 500 . The count screen displays the total number of copies used so far. The LED 511 lights up when the image forming apparatus 100 is in an operating state, for example, when the image forming apparatus 100 is executing a job or processing to store an image in the image memory 325 . The error LED 512 lights up when the image forming apparatus 100 is in an error state such as a jam or door open. The power LED 513 lights up when the main switch of the image forming apparatus 100 is ON.

FIG. 6 is an example of a screen displayed on the LCD touch panel 500 of FIG. FIG. 6A shows an example of a copy screen 600. FIG. FIG. 6B shows an example of the show-through prevention setting screen 609. As shown in FIG. FIG. 6C shows an example of the thickness selection screen 614. FIG.

6A, a copy screen 600 has buttons for calling basic functions of the image forming apparatus 100, such as a color selection button 601, a magnification button 602, and a paper selection button 603. As shown in FIG. A display field 604 displays the setting status of the function corresponding to each button. Further, another function button 605 is arranged on the copy screen 600 . When the user selects another function button 605, settings related to functions other than the basic functions, such as page printing, page aggregation, and bookbinding, can be made. Further, on the copy screen 600, shortcut buttons for calling functions frequently used by the user, such as a double-sided button 606, a finish button 607, and a show-through prevention button 608, are arranged. A double-sided button 606 is a button for performing settings related to double-sided printing. A finish button 607 is a button for setting an output mode during printing and post-processing. A show-through prevention button 608 is a button for setting a show-through prevention function for preventing show-through when reading an original. When the user selects the show-through prevention button 608 , the show-through prevention setting screen 609 in FIG. 6B is displayed so as to overlap the copy screen 600 .

The show-through prevention setting screen 609 includes an ON button 610 , an OFF button 611 , an OK button 612 and a cancel button 613 . The ON button 610 is a button for activating the show-through prevention function. The OFF button 611 is a button for disabling the show-through prevention function. For example, when the user presses an OK button 612 while the ON button 610 is selected on the show-through prevention setting screen 609 , the show-through prevention function in the image forming apparatus 100 is enabled. When the user presses the OK button 612 while the OFF button 611 is selected, the show-through prevention function in the image forming apparatus 100 is disabled. On the other hand, when the user presses a cancel button 613, the show-through prevention setting screen 609 closes without setting the show-through prevention function.

When the document detection sensor 203 detects a document, the LCD touch panel 500 displays a thickness selection screen 614 shown in FIG. 6C. On the thickness selection screen 614, the user sets the thickness of the document detected by the document detection sensor 203. FIG. The thickness selection screen 614 has buttons for setting the thickness of the document, such as a thick paper button 615 , a normal button 616 and a thin paper button 617 . In this embodiment, the thickness of the document corresponding to the cardboard button 615 is, for example, 220 g/m ² . The thickness of the document corresponding to the normal button 616 is, for example, 64-128, 157 g/m ² . The document thicknesses corresponding to the thin paper button 617 are, for example, 37, 42, and 52 g/m ² . An OK button 618 is further arranged on the thickness selection screen 614 . On the thickness selection screen 614, when the user presses an OK button 618 with one of the thick paper button 615, normal button 616, and thin paper button 617 selected, the thickness corresponding to the selected button is detected by the document detection sensor. 203 is set as the detected document thickness.

FIG. 7 is a flow chart showing the procedure of scan control processing executed by the controller unit 321 of FIG. The processing in FIG. 7 is performed by the CPU 322 of the controller unit 321 executing a program expanded from the ROM 328 to the RAM 327 . In the process of FIG. 7, it is assumed that copy screen 600 is displayed on LCD touch panel 500 .

In FIG. 7, the CPU 322 determines whether or not a document is placed on the ADF 101 based on a notification from the document detection sensor 203 (step S701).

As a result of the determination in step S701, when no document is placed on the ADF 101, the CPU 322 performs the process of step S711, which will be described later. As a result of the determination in step S701, when the document is placed on the ADF 101, the CPU 322 displays the thickness selection screen 614 on the LCD touch panel 500 (step S702). When the user presses the OK button 618 on the thickness selection screen 614 (YES in step S703), the CPU 322 determines the thickness of the document placed on the ADF 101 (step S704). In step S<b>704 , the CPU 322 determines the thickness of the document placed on the ADF 101 based on the thickness of the document set on the thickness selection screen 614 .

As a result of the determination in step S704, when the document thickness set on the thickness selection screen 614 is "normal", the CPU 322 performs the processing of step S711, which will be described later. As a result of the determination in step S704, when the document thickness set on the thickness selection screen 614 is "thin paper", the CPU 322 determines which of "ON" and "OFF" is set on the show-through prevention setting screen 609. (step S705).

As a result of the determination in step S705, when "ON" is set on the show-through prevention setting screen 609, the CPU 322 maintains the enabled state of the show-through prevention function and performs the processing of step S711, which will be described later. . As a result of the determination in step S705, when "OFF" is set on the show-through prevention setting screen 609, the show-through prevention function is disabled, so the CPU 322 enables the show-through prevention function (step S706). ) (anti-show-through function control means). That is, in the present embodiment, when the document detected by the document detection sensor 203 is thin, the show-through prevention function is enabled regardless of the settings on the show-through prevention setting screen 609 . Next, the CPU 322 displays on the LCD touch panel 500 the notification screen 801 of FIG. 8A indicating that the show-through prevention function has been activated (step S707). Next, the CPU 322 performs the process of step S711, which will be described later.

As a result of the determination in step S704, when the document thickness set on the thickness selection screen 614 is "thick", the CPU 322 determines which of "ON" and "OFF" is set on the show-through prevention setting screen 609. (step S708).

As a result of the determination in step S708, when "OFF" is set on the show-through prevention setting screen 609, the CPU 322 maintains the state in which the show-through prevention function is disabled, and performs the processing of step S711, which will be described later. . As a result of the determination in step S708, when "ON" is set on the show-through prevention setting screen 609, the CPU 322 disables the show-through prevention function because the show-through prevention function is enabled (step S709). ) (anti-show-through function control means). That is, in the present embodiment, when the document detected by the document detection sensor 203 is thick paper, the show-through prevention function is disabled regardless of the settings on the show-through prevention setting screen 609 . As described above, in the present embodiment, regardless of the settings on the show-through prevention setting screen 609, the enablement and disablement of the show-through prevention function are controlled based on the determination result of the thickness of the document in step S704. Next, CPU 322 displays on LCD touch panel 500 notification screen 802 of FIG. 8B indicating that the show-through prevention function has been disabled (step S710). Next, the CPU 322 determines whether or not the user has pressed the start key 507 (step S711).

As a result of the determination in step S711, when the user does not press the start key 507, the CPU 322 returns to the process of step S701. As a result of the determination in step S711, when the user presses the start key 507, the CPU 322 instructs the image reading unit 103 to start document reading (step S712). Upon receiving the instruction, the image reading unit 103 executes the scanning process shown in FIG. After that, the CPU 322 terminates this process.

FIG. 9 is a flow chart showing the procedure of scanning processing executed by the image reading unit 103 of FIG. The processing in FIG. 9 is performed by the CPU 310 of the image reading unit 103 executing a program expanded from the ROM 311 to the RAM 312 .

In FIG. 9, the CPU 310 determines the thickness of the document placed on the ADF 101 (step S901). In step S<b>901 as well as in step S<b>704 , the CPU 322 determines the thickness of the document placed on the ADF 101 based on the thickness of the document set on the thickness selection screen 614 .

As a result of the determination in step S901, when the thickness of the document set on the thickness selection screen 614 is "normal", the CPU 310 performs the processes after step S903, which will be described later. As a result of the determination in step S901, when the document thickness set on the thickness selection screen 614 is either "thick paper" or "thin paper", the CPU 310 performs the process of step S902. In step S902, the CPU 310 notifies the CPU 300 of the ADF 101 to control the document transport speed to a low speed (transport speed control means). Upon receiving this notification, the CPU 300 reduces the rotation speeds of the motors that drive the transport rollers 208, registration rollers 209, transport rollers 212, transport rollers 213, large rollers 211, and discharge rollers 215 to predetermined rotation speeds. As a result, the document transport speed is controlled to the second speed lower than the preset first speed, which is the normal speed. For the second speed, it is taken into consideration that the discharged thin paper document is sufficiently dropped onto the document discharge tray 216 and that the torque of the thick paper document does not become insufficient at the curved portion of the conveying path (conveying path) in the ADF 101 . speed, for example half the first speed.

Next, the CPU 310 starts feeding the document (step S903) and reads the image data (step S904). The read image data is transmitted to the controller unit 321 and stored in the image memory 325 via the scanner IF 324 . Next, the CPU 310 instructs the controller section 321 to perform image processing on the image data stored in the image memory 325 (step S905). The controller unit 321 that has received this instruction performs various image processing on the image data stored in the image memory 325 . For example, when the show-through prevention function is enabled, the controller unit 321 executes the show-through removal image processing of FIG. 10, which will be described later. Next, CPU 310 determines whether or not any documents remain in document tray 201 (step S906).

As a result of the determination in step S906, if there are documents left in document tray 201, CPU 310 returns to the process of step S903. As a result of the determination in step S906, if no documents remain in the document tray 201, the CPU 310 terminates this process.

FIG. 10 is a flow chart showing the procedure of the show-through removal image processing executed by the controller unit 321 of FIG. The processing in FIG. 10 is performed by the CPU 322 of the controller unit 321 executing a program expanded from the ROM 328 to the RAM 327 .

In FIG. 10, the CPU 322 reads image data stored in the image memory 325 via the scanner IF 324 (step S1001). Next, the CPU 322 determines whether or not the show-through prevention function is activated (step S1002).

If the result of determination in step S1002 is that the show-through prevention function is not activated, the CPU 322 terminates this process. As a result of the determination in step S1002, when the show-through prevention function is enabled, the CPU 322 generates a histogram from the luminance level of the image data (step S1003). Next, the CPU 322 determines the background level from the generated histogram (step S1004). FIG. 11A shows that characters 1102 show through in read image data 1101 obtained by scanning. When the read image data 1101 is composed of a character image on the front side and a character image 1102 showing through, for example, a histogram 1103 in FIG. 11B is generated. In the histogram 1103, the horizontal axis indicates 0 to 255, and the vertical axis indicates the value obtained by counting pixels of that brightness. The CPU 322 determines the background level from the histogram 1103, for example. As for the method of determining the background level, a portion other than the background luminance 255, which has a high density, for example, the luminance 195 indicated by 1104 in FIG. 11B is determined as the background level. Next, the CPU 322 sets a coefficient for removing the background based on the background level determined in step S1004. Next, the CPU 322 executes background removal processing based on the set coefficients (step S1005). As a result, for example, the image data 1105 shown in FIG. The CPU 322 then terminates this process.

According to the above-described embodiment, when the document detected by the document detection sensor 203 is thin, the show-through prevention function is activated. Thereby, the show-through removal image processing can be applied to the read image data, thereby preventing the output of the show-through data. In the above-described embodiment, when the document detected by the document detection sensor 203 is thin, the document transport speed is controlled to the second speed lower than the preset first speed. As a result, it is possible to prevent the trailing edge of the document from colliding with the leading edge of the succeeding document when the document is transported, thereby preventing the occurrence of a situation such as a jam or stacking failure during transport of the document. That is, in the above-described embodiment, it is possible to suppress the output of the show-through data while suppressing the occurrence of jams and stacking failures during document transport.

Further, in the above-described embodiment, when the document detected by the document detection sensor 203 is thick paper, the show-through prevention function is disabled. As a result, it is possible to prevent unnecessary image processing for removing show-through from being performed on the read image data obtained by reading a thick paper document that does not cause show-through. As a result, it is possible to avoid a situation in which part of the read image data is lost due to the execution of the image processing. Further, in the above-described embodiment, when the document detected by the document detection sensor 203 is thick paper, the transport speed is controlled to the second speed. As a result, it is possible to prevent the load on the conveying roller from becoming high at the curved portion of the conveying path in the ADF 101 when conveying the thick original, thereby preventing the occurrence of a jam when conveying the thick original. be able to. That is, in the above-described embodiment, it is possible to prevent the occurrence of a jam when conveying a thick original while avoiding a situation in which part of the image data is lost due to execution of unnecessary image processing.

In the embodiment described above, regardless of what the user selects on the show-through prevention setting screen 609, the enablement and disablement of the show-through prevention function is controlled based on the determination result of the thickness of the document in step S704. . As a result, even if the user has not properly set the show-through prevention function on the show-through prevention setting screen 609 or has forgotten the above setting, the show-through prevention function can be appropriately set according to the thickness of the document. Settings can be controlled.

Further, in the embodiment described above, when the user selects the OFF button 611 on the show-through prevention setting screen 609 and the document detected by the document detection sensor 203 is thin paper, the show-through prevention function is enabled. In this case, a notification screen 801 is displayed on the LCD touch panel 500 to notify that the show-through prevention function is to be activated. On the other hand, when the user selects the ON button 610 on the show-through prevention setting screen 609 and the document detected by the document detection sensor 203 is thick paper, the show-through prevention function is disabled. In this case, a notification screen 802 is displayed on the LCD touch panel 500 to notify that the show-through prevention function is to be disabled. As a result, it is possible to notify the user that the settings of the show-through prevention function are different from those selected by the user on the show-through prevention setting screen 609, so that the setting status of the show-through prevention function can be notified to the user. can be grasped.

Although the present invention has been described using the above-described embodiments, the present invention is not limited to the above-described embodiments. For example, instead of setting the thickness of the document on the thickness selection screen 614 , the thickness of the document may be set based on the detection result of the sensor provided in the ADF 101 . For example, a light projecting section and a light receiving section may be arranged so as to sandwich the document in the document transport path, and the thickness of the document may be determined based on the amount of light received by the light receiving section through the document. By doing so, it is possible to save the user the trouble of setting the thickness using the operation unit.

Further, in the above-described embodiment, types other than thick paper, normal paper, and thin paper may be set as options for the thickness of the document to be set. For example, "postcard", "coated paper", and "copy of form" can be set, and if it is "postcard", it is set to thick paper, and if it is "copy of form", it is set to thin paper. good. By processing in this manner, even if the user does not know the thickness of the document, it is possible to set an appropriate thickness based on the paper type.

Furthermore, in the above-described embodiment, the grammage may be set as a method for setting the thickness of the document. If the paper type of the document to be scanned is determined, the basis weight may be selected from preset basis weights in the operation unit 326 when the original is read, or the basis weight may be input. By processing in this manner, the thickness of the document can be accurately determined from the grammage.

The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus reads the program. It can also be realized by executing processing. The invention can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

100 image forming apparatus 103 image reading units 310 and 322 CPU
321 Controller unit 609 Show-through prevention setting screens 801 and 802 Notification screen

Claims (10)

a conveying means for conveying the document placed on the document tray;
An image processing apparatus comprising reading means for reading an image of the document conveyed by the conveying means,
detection means for detecting that a document is placed on the document tray;
display means for displaying an object for receiving the thickness of the document from a user at a predetermined timing on condition that the detection means detects that the document is placed on the document tray;
When the thickness of the document received by the object is the first thickness, the document is transported by the transport means at a first transport speed, and the thickness of the document received by the object is the first thickness. and control means for causing the conveying means to convey the document at a second conveying speed slower than the first conveying speed when the document has a second thickness greater than the first thickness. Device. 2. The image processing apparatus according to claim 1, wherein a show-through prevention function for said document is enabled based on information indicating the thickness of said document. When the thickness of the document received by the object is the second thickness, the thickness of the document received by the object is thinner than the first thickness without enabling the show-through prevention function. 3. The image processing apparatus according to claim 2, wherein a function of preventing show-through of the document is enabled when the document is thick. When the thickness of the document received by the object is the third thickness, the control means causes the transport means to transport the document at the second transport speed. The image processing apparatus according to claim 3. 5. The image processing apparatus according to claim 2, further comprising notifying means for notifying that the show-through prevention function is enabled. 6. The image processing apparatus according to any one of claims 1 to 5, wherein the conveying means conveys the document via a curved conveying path. 7. The image processing apparatus according to claim 1, further comprising printing means for printing the image of the document read by the reading means. 7. The image processing apparatus according to claim 1, further comprising transmitting means for transmitting image data generated based on the image of the document read by the reading means. A control method for an image processing apparatus having transport means for transporting a document placed on a document tray and reading means for reading an image of the document transported by the transport means, comprising:
a detection step of detecting that a document has been placed on the document tray;
a display step of displaying an object for receiving the thickness of the document from a user at a predetermined timing on condition that the detection step detects that the document is placed on the document tray;
When the thickness of the document received by the object is the first thickness, the document is transported by the transport means at a first transport speed, and the thickness of the document received by the object is the first thickness. and a control step of causing the conveying means to convey the document at a second conveying speed slower than the first conveying speed when the document has a second thickness greater than the first thickness. How to control the device. A program that causes a computer to execute the control method of the image processing apparatus according to claim 9 .

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